X-Wings and the Rectangle Rule for Solving Medium to Hard Sudoku Puzzles

[@hilaydt]

I've watched many other videos and read tutorials on how to do X wings and I never understood until I watched your breakdown. Thanks so much for the clear explanation!

[@majaber1]

me too

[@rameshramasamy21]

Me too

[@leemelbourne-weaver4337]

ME too

[@soniaperezcaceres3935]

Same!!!!

[@RandomThingsEn]

SAME! the other tutorials didn't really mention the rows part

[@rameshramasamy21]

Thank you for clearly explaning. I was not able to resolve a sudoku and didn't sleep for 5 days. Your video rescued me.

[@jballenger9240]

The clearest explanation I’ve heard of the X-wing. Thank you m

[@r.mcd2921]

Thank you - this was the first explanation that made sense to me.

[@flynn1a]

I have watched several x wing videos and couldn’t get the gist of what they were saying. But you made it so simple and so obvious! Thank you!!!!

[@rajeshwarichauhan4257]

I had been trying to understand this pattern from many videos ...but u explained it so clearly...i got it in a minute..❤🌻

[@LearnSomethingNewEveryDay]

Glad to hear that, thanks for the comment!

[@StephenRahrig]

Why are you calling it a 2 x 2

[@oingomoingo7411]

ya i also dont get it

[@florian2442]

My guess is that in Sudoku an "A x B" rectangle is defined where A and B represent the amount that a candidate number shows up, and not how many spaces they are apart. For example a "2x1" rectangle is any rectangle that connects 2 candidate numbers on their row/columb no matter how far apart they are

[@SmartHobbies]

Great straightforward explanation of X-wings. I always found it interesting that 2x2 are called “wings” where 3x3, 4x4, etc. all are “fish”. I look forward to watching more of your content.

[@LearnSomethingNewEveryDay]

Thanks Smart Hobbies.....yes it is interesting how these are called exotic fish names.....thanks for your support, I appreciate it! Good luck with your channel, it looks interesting....I just subbed!

[@JonJacks]

Okay wow! I've seen the X wing so many times and never thought there was a strategy. THANK. YOU.

[@kalpanasarkar9331]

Best explanation of x wing I've come across so far

[@robertvolm3609]

So, does this mean that a "X" is always a 3 square by 4 square grid? Can it be 4 squares by 5 squares? Or anything different?

[@mattnorton3285]

Apologies if I'm missing an obvious implication, but for the part of the video from 1:26 to 1:34, why must the 2 in column 7 be the correct one? Why couldn't the 2 in column 8 be correct? (and same question for the 2 in column 9 in row C)

[@fire285]

Hey, the square is the only option for these numbers. We know 2 must be present in column 4 and 7 and that all other options in column 4 and 7 cannot hold a two. As a generalized rule, if a square exists where either a row or column requires a number to be in the square then both the row and column require the numbers to be in the square.

[@love4music25]

can you expand further? @@fire285 I still didnot get it

[@hebum]

I was wondering about the same thing but if you look at the column 7 , 2 can be placed in only in the A or C rows for that column so we wouldn't even mark 8A or 9C as possibilities 🤦‍♂

[@kallisto9680]

​@@hebumThanks for helping. Now I understand ☺️.

[@hebum]

@@kallisto9680 👍

[@BillSmith-bd1yv]

Sorry, I don't understand why we would call an area of 4 squares by 3 a "2x2 rectangle" and if it really was 2x2 then wouldn't it be a square? Asking for clarification because I can see lots of potential candidate configurations, but they can't all be usable. Thanks in advance.

[@pepitocovid-91]

THANK YOU SO MUCH FOR THE EXPLANATION, THIS WILL HELP ME SO MUCH

[@claudegiguere8731]

straight to the point and excellent explanations 👍 Thanks a lot !!!

[@fanofipa]

Natural teacher!!

[@faisalrezhaRakhman]

Easy to understand, thanks alot.

[@david1benson2jonas]

Great video, super easy to understand. Thank you!

[@Bromang-n4h]

Thanks for the tutorial!

[@martinaperez9594]

Such an useful trick! I'll implement it, thanks!

[@timothymarchant]

so what happens with the annotated number outside the rectangle but in the same box but it's in the middle/ For example if Cell B9 had a 2 candidate as well would that justify removing that candidate?

[@PhillipFlop3327]

I was wondering the same thing

[@aubreymaichi4600]

omg finally a vid that's easy for me to understand😢

[@andyn6053]

Very good. Others couldnt explain this to me.

[@ruatoomey9107]

Top class, thank you

[@Brathadoir]

Best explanation ever.

[@kskaliprasadkotagal6468]

Thanks for sharing this idea of elimination

[@believeinaction]

Love from India 🤩🤩🤩🔥🔥

[@Pladdabus]

I finally get it, thank you for this!!

[@blainenewton7188]

Excellent explanation.

[@NightSovereign]

what does 2x2 stand for? And why is the rectangle 4x3 is called so?

[@tomcat1184]

wow thank you for this !!!!

[@yennisutedjo4173]

Nice explanation

[@lindac6147]

I’m confused . You state when referring to the first example ( ~3:00) with “2” that they are identified to be part of an x wing if the candidate only appears twice. However “2” appears three times on row A?

[@groslou9997]

You have to think in columb

[@groslou9997]

Column 7

[@diramaking4302]

@@groslou9997 Thanks bro. This is what was confusing me for so long. I am quite good at sudoku and I was confused how I am not understanding what everyone is calling a simple technique. I can't believe I was overlooking this... I have been using this for so long without realising it...

[@elkabat5205]

​@@groslou9997okay but then I don't need the X-wing right? If I can see that no other 2 can appear in column 7 then its obvious that rows 1 or 3 must have a 2. Am I missing something?

[@kevinklise7036]

A good explanation. However, I need to ask for a couple points of clarification. If the particular number being used as the four corners of the rectangle (in this video, it was a "2"), then all the other 2's in that row can be eliminated. Does that include the 2's that are ONLY OUTSIDE the rectangle? Or can it include the 2's (if any) BETWEEN the four corners of the rectangle?

[@eugenetswong]

Yes, between and outside. I remember it this way: it doesn't matter how you find the rectangle; eliminate all of them in the columns and rows, except the 4 corners.

[@muhammadzakyyahya1625]

I still don't understand the first example..

[@abhishekshandilya273]

Me too were you able to figure it out? I mean lets assume the 2is in A4 although this eliminates 2 from row A yet still the 2 can still be in C7 or C9. How can C9 as a candidate for 2 be eliminated? Same problem with A8 if we assume C4 to be 2

[@hieutv.thebattlecats]

very nice

[@179Kreator]

Hello, I applied it in a an expert sudoku and it didn’t work

[@divermike8943]

Why do you say it is a 2x2 retangle? The first example with the 4s is three rows by four columns. So is the second example with the 2s. Does the size of the retangle even matter?

[@DiederdirkDusty]

The size doesn't matter, only that 2 colomns/rows contain 4 cells where a candidate can go and form a x-pattern.

[@garondes1]

I just don’t get it, there are other numbers that repeat also like the 6 7 and 8, why don’t they form an X wing? why choose the 2 in particular?

[@dras227]

how it is an X pattern? if 2 in A4 is true, then both 2's in C7 and C9 can be true

[@MacXpert74]

They can't because you need to look at the columns in this case. In both column 4 and column 7 the ONLY 2's are in row A & C, therefore forming a X-wing, this then allows to eliminate any other 2's in those rows. Because if you would place the 2 in C9, you can't place any 2's anywhere in column C7, which would make the Sudoku invalid.

[@scorbett4370]

Is this rectangle referred to as a 2 by 2 because it involves 2 Blocks AND 2 Rows AND 2 Columns? Thank you for the video.

[@royalbloodedmutt]

Finally an explanation that makes sense!!! Bless you.

[@26472989]

Let me try this.

[@kenjohnson4645]

Would if be possible to get the name or link of the Sudoku program that you use in your tutorials as I wanted a program that would allow the user to take advantage of or have the ability to use a "Red X" or similar markings.

[@jet8485]

But how do you know which number you have to pick in the x wing. Because there are 4 numbers 4, but also 4 numbers 7 and 4 numbers 8 in the same spot. 🤔

[@albythegreat4648]

Still unsure if that's really a fact you can eliminate the other numbers in the same group or not. Couldn't the 2 still possibly be in the other 2 spots?

[@eyefeelpineal4079]

Yeah that's what I'm struggling with

[@sudharshank8256]

This method doesn't work. I wonder how this video got so many positive comments

[@ancho-31337]

No, because those are the only sets of 2s in columns 4 and 7.

[@frfr335]

I still don't understand this. At 3:28m you say 'Looks for a number that only appears twice in a line..." but then you use 2 separate examples in which the number appears either 3 times (the '2's example) or 4 times (the '4's example) in the lines. Could someone clarify please?

[@robertnutt4944]

Hi, how does this work in a 16 x 16 Sudoku? Any different?

[@daretowin100]

I dont get it.. let say if A4 is not 2 why can't A8 be 2 and similarly if C4 not is 2 why can't c9 be 2

[@danielkirby3079]

I’m sorry, I listened to the video several times and I never understood where you explained which was the correct 2. One of the comments was between 1:26-1:34 of your video but I didn’t catch it. I did hear where you spoke of eliminating other 2’s in actual rows but couldn’t discern which 2 you picked in the x-wing. Most of the comments seem to be happy with your explanation so I am sure it’s just my ADD or lack of understanding. Could you please explain how you picked the correct 2 in the x-wing and not how you eliminated the other 2’s?

[@kennethwoodby4528]

what does it mean when we say that a cell cant see eachother

[@LearnSomethingNewEveryDay]

these are also called "peer" cells, they are either in the same block, row, or column, then they "see" each other. Hope that helps.

[@sureshpreeth]

Will u solve my puzzle which I was stuck, all repeated numbers can't be filled, will u

[@Fenar_]

Can someone explain why the twos in column 8 and 9 wouldn't be a possibility?

[@RusNad]

Because column 7's twos have to be in the top right box, that already eliminates the twos in column 8 and 9

[@RusNad]

But I think even if they were across different boxes, the x-wing means that if A8 was two, then C4 and C7 would both have to be two, which is impossible.

[@oksanaball6494]

Why did you pick number 2 and not 6,7 or 8? Number 4 and not 5, 6, 7 or 8?

[@kaneshoots]

I still can't understand why you choose the 2's in the beginning as there are also, 6s 7s 8s

[@jussikankinen9409]

What about the 678

[@aninterviewwith...1702]

I'll have to come back to this one. I still don't get it.

[@SmedleyAndrea]

431 Kuhn Inlet

[@alg4943]

Does anyone ever find more than one X-Wings in a puzzle?

[@elgiztaghiyev3194]

There only "E and H" has 2 it means automatically A and C has to have 2 you explain more harder than I think

[@florinprisecaru4809]

Why did you eliminate those 2 ? Why should we keep 2 from A7 and not from A8 and C9 column? For me has no logic. Sorry It would be al right if we eliminated all 2 from column 4 and 7. But in this situation 2 can be in A7 and A 8 50 % 50% and the same C and C9.

[@MikeKey91]

Everytime I use this I get a mistake. Still no clue.

[@TunioS19]

Sorry but I think THIS IS NOT X-wings technique. At example 1, in column 7, there only 2 possibilities for number 2 (A7 & C7) and they also in the same Square 3. Therefore in Square 3, we can eliminate the others number 2 at A8 & C9. There's no need to use 2 number 2 in column 4 as she called this X-wings. (The similiar thing at example 2...). I think she should use other examples for this technique.

[@juliafullbusterdododotanmh6837]

I agree

[@raghureddy1746]

I would like disagree as that is not quite right. As I mentioned in another comment, it is the fact that in columns 4 and 7 there are only two 2s, and they form an X pattern. If it wasn’t for the X pattern, you really cannot eliminate the other twos in the box like you have mentioned just because there are two 2s in that box.

[@betmenizorahovice4843]

this looks like cheating to be honest, x wings is too powerful and much more easier to spot that xy wings

[@groslou9997]

What is the method to resolve this sudoku please ? May you resolve fully this sudoku in an other vidéo for exemple plz ?

[@kvothe2144]

This video: Let me repeat myself 30 times.

[@ted5669]

It’s not a 2x2 rectangle, that would be a square

[@danbird1903]

The 4s example is bad because you could eliminate those same 4s without using the x wing….

[@RR-ip3yk]

a little bit time comsuming

[@joe-lz2lt]

i didnt understand at all ....could have been easier if she had filled in

[@AbhijeetSonkusare]

gave very bad examples of x-wing. Provided wrong explanation of why the 2 in column 8 and column 9 should not be present. Correct explanation is that in column 7 the 2 can only come in row A and row C, thus removing other possibilities for that box.

[@sassos2738]

N'importe quoi

[@Zadrazar]

This is wrong

[@steveloudon7491]

Why do you say that

[@sudharshank8256]

​@@steveloudon7491because she ignored other "2" possibilities in the 3rd box